T7ENIA. 
the attack to leeward is most favourable to 
the retreat of your men ; besides, it is far 
easier to cast off from tlie enemy, than 
it would be if you were to windward of 
her. 
TiENIA, in natural history, tape-worm j 
body flat, and composed of numerous arti- 
culations ; head with four orifices for suc- 
tion, a little below the mouth : mouth ter- 
minal, continued by a short tube into two 
ventral canals, and generally crowned with a 
double series of retractile hooks or holders. 
Gmelin has enumerated almost one huri- 
dred species, besides varieties r he has di- 
vided them into sections. A. Those found 
in other parts besides the intestines, and 
furnished with a vesicle behind. B. Those 
found in the intestines only, and without a 
terminal vesicle. C. Those with the head 
unarmed with hooks. The worms of the 
first section are found infesting Mammalia, 
reptiles, and fish. Those of the second sec- 
tion are found in the Mammalia, in birds, 
and in fish ; and those of the third section 
infest Mammalia, birds, reptiles, and fish. 
This genus of worms are destined to feed 
on the juices of various animals, and ate 
usually found in the alimentary canal, gene- 
rally at the upper part of it. They are 
sometimes found in great numbers, and oc- 
casion the most distressing disorders. They 
have the power of reproducing parts which 
have been broken off, and are therefore 
removed with the utmost difficulty : they 
are oviparous, and discharge their eggs from 
the apertures on the joints. We shall give a 
few of the more remarkable species. 
1. T. visceralis, which is inclosed in a 
vesicle, broad in the fore part, and pointed 
in the hinder part; inhabits the liver, the 
placenta uterina, and the sac which con- 
tains the superfluous fluid of dropsical per- 
sons. 2. T. cellulosa, which is inclosed in a 
cartilaginous vesicle, inhabiting the cellular 
substance of the muscles ; is about an inch 
long, half an inch broad, and one-fourth of 
an inch thick, and is very tenacious of life. 
3. T. dentata, has a pointed head; the 
large joints are streaked transversely, and 
the small joints are all dilated; the oscuhim 
or opening in the middle of both margins is 
somewhat raised. It is narrow, ten or 
twelve feet long, and broad in the fore 
parts : its ovaria are not visible to the naked 
eye; and the head underneath resembles a 
heart in shape. It inhabits the intestines. 
4. T. lata, is white, with joints very short 
and knotty in the middle ; the osculum is 
solitary. It is from eighteen to ooe hun- 
dred and twenty feet long; its joints are 
streaked transversely; its ovaria are dis- 
posed like the petals of a rose. 5. T- 
vulgaris, has two lateral mouths in each 
joint ; it attaches itself so fiinily to the in- 
testines, that it can scarcely be removed by 
the most violent medicines; it is slender, 
and has the appearance of being mem- 
branaceous ; it is somewhat pellucid, from 
ten to sixteen feet long, and about four 
lines and a half broad at one end. 6. T, 
trnttae, which chiefly inhabits the liver of 
the trout, but is also to be fomid in the in- 
testines of the human species. 7. T. so- 
lium, has a marginal mouth, one on each 
joint. 8. , T. ovilla, found in the liver 
and omentum of sheep. 9. T. celebralis 
is aggregate ; numerous animalcules united 
by their base to a large common vesicle, 
distributed about the surface and retractile 
within it. This is found in vast numbers in 
the brain, or spinal marrow, immediately 
beneath the brain of sheep. Tlrese no- 
xious animalcules occasion giddiness and 
staggering, and the disease known by the 
name of the dunt or rickets: which if the 
containing vesicle be broken, is inonrable ; 
for these minute worms, in size scarcely 
larger than a grain of sand, are each of 
them furnished with from thirty-two to 
thirty-six hooks on the head, by which they 
fix themselves firmly to the substance of 
the brain, or its coats. 
Tlie structure and pljysiology of the tae- 
nia are curious, and it may be amusing as 
well as instructive to consider it with at- 
tention. The tcenia appears destined to 
feed upon such juices of animals as are al- 
ready animalized ; and is therefore most 
commonly found in the alimentary canal, 
and in the upper part, where there is the 
greatest abundance of chyle ; for chyle 
seems to be the natural food of the toenia. 
As it is thus supported by food which is al- 
ready digested, it is destitute of the com- 
plicated organs of digestion. As the TJ 
solium is most frequent in this country,, it 
may be proper to describe it more particu- 
larly. 
It is from three to thirty feet long, some 
say sixty feet. It is composed of a head 
in which are a mouth adapted to drink up 
fluids, and an apparatus for giving the head 
a fixed situation. The bod)' is composed 
of a great number of distinct pieces arti- 
culated together, each joint having an or- 
gan by which it attaches itself to the neigh- 
bouring part of the hmer coat of the intes- 
tine, Tire joints nearest the head are al- 
